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More Juno

August 2, 2011

The solar system's largest planet is putting on a good show right now. Jupiter rises not long after midnight, and is high in the southeast at first light. It looks like a brilliant star. It outshines all the true stars, and it's in a fairly barren patch of sky, so it really stands out.

One of the reasons that Jupiter shines so brightly is that it's big -- about 11 times the diameter of Earth. Another is that it's topped by bright clouds.

No one's quite sure just how deep the clouds go. We do know that Jupiter doesn't have a solid surface. It probably has a small, dense core, surrounded by a layer of metallic hydrogen, surrounded by hydrogen and helium gas.

The exact structure should become a lot clearer when a craft known as Juno arrives at Jupiter in 2016. Its launch window opens on Friday.

From orbit around Jupiter's poles, Juno will see the planet's entire atmosphere down to depths of dozens of miles -- mapping its composition and structure, and how it circulates.

Juno will also map Jupiter's magnetic and gravitational fields, allowing scientists to learn more about everything below the atmosphere, all the way down to the core. And it'll study the power source for Jupiter's aurorae.

Juno is scheduled to orbit Jupiter for one year. When its mission is over, it'll burn up as it's sent plunging into Jupiter's atmosphere -- an atmosphere that we should know a lot more about -- thanks to Juno.

We'll talk about another giant planet tomorrow.


Script by Damond Benningfield, Copyright 2011


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